KABUL, Afghanistan (AP) -- A member of a U.S.-backed Afghan village police force killed nine of his fellow officers as they slept Friday in a volatile eastern area, officials said. The Taliban claimed responsibility.

The gunman opened fire with his assault rifle after waking up at 3 a.m. ostensibly to take over guard duty at a small command post for the Afghan Local Police in Paktika province, killing everybody inside, including the post's commander, according to officials. He then took their weapons, piled them in a pickup truck and sped away.

It was the latest in a growing number of attacks by Afghan security forces against their own people or against international troops in Afghanistan in recent years, some the result of arguments and others by insurgent infiltrators.

Provincial police chief Dawlat Khan Zadran said the incident took place in Yayakhil town of Yayakhil district.

Bowal Khan, chief of Yayakhil district, identified the gunman as Asadullah and said he goes by one name, as do many Afghans.

Khan said his own brother was among those killed, along with the commander of the post, identified as Mohammad Ramazan, and two of the commander's sons.

The motive for the killing was not known, but police in the area blamed the Taliban for the attack. Paktika is a stronghold of the Haqqani network, a Pakistani-based group with ties to the Taliban and al-Qaida. Although they mostly attack U.S.-led coalition forces, they have often carried out assaults and bombings against the Afghan army and police.

Taliban spokesman Zabiullah Mujahid claimed responsibility for the attack and said the shooter was a member of the insurgent group. He added in a text message that he took the dead police officers weapons and handed them over to the Taliban.

"This man is a coward. What he did is part of the Taliban conspiracy," Khan said.

Khan and Zadran said the killer's two brothers were being held for questioning.

The increasing number of attacks by Afghan police and soldiers has cast doubt on the readiness of Afghan security forces to take over their own security as the U.S.-led international coalition prepares to end its combat mission by the end of 2014.

On Monday, an American soldier was shot and killed by a member of the Afghan Local Police, at a checkpoint in Paktika.

Two British soldiers also were killed by an Afghan soldier in front of the main gate of a joint civilian-military base in southern Afghanistan that day.

So far this year, 16 NATO service members have been shot and killed by Afghan soldiers and policemen or militants disguised in their uniforms, according to an Associated Press tally. That equals 18 percent of the 84 foreign troops killed this year in Afghanistan. Of the approximately 80 NATO service members killed since 2007 by Afghan security forces, more than 75 percent were in the past two years.

There also have been recent examples of Afghans killing their own comrades.

The Afghan Local Police, or ALP, provide security in villages and remote areas that cannot be staffed by the Afghan army and police.

U.S. special forces have been training the village-level fighting forces in hopes of countering the Taliban insurgency - a concept similar to the one that turned the tide of the Iraq war. The ALP, however, is commanded and run by the Afghan government and police.

The initiative has stirred worries it will legitimize existing private militias or create new ones. Warlord-led militias ravaged Afghanistan in the 1990s, opening the way for the Taliban takeover.

But Taliban infiltration of the ALP is considered difficult as all their members are recruited locally and vetted by village elders before joining. They usually guard the village or area where they are recruited and know each other.

Another ALP member was accused of involvement in the killing of nine members of his unit in March in southern Uruzgan province. They also were shot and killed while asleep at their post in the village of Oshi in the province's Charchino district. It remains unclear if he killed them or allowed a killer into the post, but he was never apprehended.

In other violence Friday, a motorcycle bomb parked by the side of a road exploded, killing an Afghan police officer and wounding another in Sangin district of southwest Helmand province, police said. They added that another police officer was shot and killed late Thursday outside his house in the capital of Helmand.

NATO also said Friday that two of its service members were killed in southern Afghanistan - one died in a roadside bomb explosion on Friday and the other one in an insurgent attack on Thursday. NATO did not disclose any other details.

So far this year, 88 international troops have been killed in Afghanistan.

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Associated Press writers Patrick Quinn in Kabul and Mirwais Khan in Kandahar contributed to this report.